In a large mixing bowl, add all ingredients except the short ribs and salt. Whisk until thoroughly combined.
Rinse short ribs under cold water to wash away any shards of bones that occurred during butchering. Pat ribs dry with paper towel. Season both sides lightly with kosher salt. (Seasoning the meat directly vs. the marinade allows you to gauge exactly how much salt is required)
Add seasoned short ribs to a large, zip-top bag and pour in the marinade. Seal the bag and massage the marinade all over the meat. Open a corner of the seal, squeeze out all the air, then close the bag. Place bag on a tray or plate and refrigerate overnight or at least 4 hours.
When ready to grill, remove ribs from marinade and place on a tray lined with paper towel. Pat very dry with paper towel.
Transfer reserved marinade to a small stockpot. Add ½ cup of water and cook over med-low heat until reduced by half. Transfer reduced sauce to a serving bowl and set aside.
Preheat the OptiGrill Smart using the steak pre-set. Grill ribs in batches, with lid closed, approximately 4 minutes or until the pre-set cooking mode time has elapsed. Tip: as the meat cooks, it will reduce in size. For perfect grill marks, alternate stacking the ribs one atop the other to achieve direct contact with the grates (see @primal_gourmet Instagram Stories for demonstration).
Transfer grilled ribs to a serving platter and brush one side with reduced sauce. Garnish with sesame seeds and thinly sliced green onion. Serve with cauliflower rice and an assortment of side dishes, such as kimchi, sautéed mushrooms, and Korean pickles.